Using extremely large objects and small objects in the same scene?
As mentioned, another option is to use Forced Perspective. This is where an object's distance appears to be different to its actual distance due to how it appears and/or moves.
By placing an object in the middle-distance and parenting it to the Camera's location, it can move as if it were actually placed &quot;at infinity&quot; - so that it moves in relation to the background.
This can be achieved using the 'Child of' constraint with the settings set to enable Location but to disable rotation (since we want its position to be based on the viewpoint but not to be affected by the rotation of the camera).

Here's the result using the default cube and a default size icosphere placed at a slight distance. Note that I've added some static stars to the background to make it more apparent that the sphere is appearing static in relation to the background and making it appear more ‘planet sized’ since it doesn’t change as the camera moves around the foreground objects :

Blend file included for reference